Telemeter.



V. COLZI & F. BARDELLI.

TELBMBTBR.

APPLICATION FILED MAR. 3. 1910.

l ,1080,42 1 Patented Dec. 2, 1913.

3 SHBETS-SHEET 1.

N 1fy R 1%: PIV/IP /P V. COLZI @c F. BARDELLI.

TBLBMETER.

APPLICATION FILED MAILS, 1910A Patented Dec. 2, 1913.

3 SHEBTS-SHEET 2.

V. COLZI & F. BARDELLI.

TELBMBTER.

APPLIOATION FILED Mmm. 1010.

Patented Dec. 2, 1913.

3 SHEETS-SHEET 3.

/Ezwdded/ COLUMBIA PLANOQRAPM 1:0.,WASmNOTON. u4 c.

STATES PATENT OFFICE.

VIRGILIO COLZI AND FELICE BARDELLI, 0F TURIN, ITALY.

TELEMETER.

To all 'whom t may concern:

Be it known that we, VmeILio Comi and FELICE BARDELLI, both subjects ofthe King of Italy, residing at 1S Via Roma, Turin, Italy, have inventedcertain new and useful Improvements in Telemeters; and we do herebydeclare the following to be a full, clear, and eXact description of theinvention, such as will enable others skilled in the art to which itappertains to make and use the same, reference being had to theaccompanying drawings, and to letters or figures of reference markedthereon, which form a part of this specification.

The present invention relates to telemeters having a fixed base andinstantly giving the distance of a distant object sighted, by a singleobservation, and has for its object improved moditications of thetelemeter described in our Patent No. 1,058,556, dated April 8, 1913.

The main features of the present improvement relate to the telescopicsystem, the measuring device, the rectifying device, and the means fo-rsupporting or suspending the instrument, as will hereinafter be morefully described and particularly pointed out in the claims.

In the accompanying drawings, showing by way of example, one form of ourimproved telemeter, and in which like parts are similarlydesignatetl-Idigure l shows the field of the eye piece or ocular of thetelemeter. Fig. 2 is a perspective view of the central system oferecting prisms and the associated prisms of the rectifying system.Figs. S and 3a are diagrams showing the action of a rotating prism on aluminous ray. F 4l and 5 show prisms forming the optical part of ameasuring device having, respectively, two and three prisms and made andoperating in accordance with the presentinvention. Fig'. 6 is adiagrammatical elevation of the telescopic and rectifying systems. Fig.7 is a horizontal longitudinal section through the telemeter on line 7 7of Fig. 1Q. Fig. 8 is an elevation of one of the prisms of theobjectives. Figs. t) and l0 show the field of the eye piece of therectifying system in two positions. Fig. 11 shows the telemeter in rearelevation with its supporting tube in vertical longitudinal section.Fig. 12 is a front elevation. Fig. 13 is a section on line 13"-13 ofFig. 11. Fig. 14: is a cross-section showing the Specification ofLetters Patent.`

Application filed March 3, 1910.

Patented Dec. 2, j 913.

Serial No. 547,137.

relative position of the oculars and the separating prism.

It has been found in practice that the upper and lower portions of theimage, 1 and 2, Fig. 1, are simultaneously visible in a diminished orpaler condition, as indicated at 3 and 4l, notwithstanding the use ofthe thin opaque plate or sector 5 in the horizontal plane of thedivision between the upper and lower halves of the images at the eyepiece. Such phantom image, or double representation, is confusing tounskilled observers, and it is desirable that the two portions 1 and 2only of the image be visible in the eye piece. It also causes the imagesat ordinary dis tances to be less distinct. IVe have overcome thisobjection and annoyance to unskilled observers by cutting the prism ofthe erecting system, I4 Q, in the plane of reflection 7 o-f the opaquesector 5, vf. c., in a plane parallel to the emergent face of the prism,and cementing the parts together again. The

plane 7 constitutes therefore a sort of prolongation of the sector 5 inthe direction of its reflection and prevents the oblique luminous raysfrom near the `junction of the two prisms, S, 9, from passing beyondthis plane. The images 1 and 2, Fig. 1, are rendered clear, and thoseless sharp, or phantom, images, 3 and 4l, are avoided.

The measuring device, which is the most important part of the presentinvention, consists in its essential form of two prisms whose refractingedges are adjacent and parallel, so that when in closed position theyact substantially as a single glass having parallel or nearly parallelfaces. In the present invention these two prisms are mounted to rotatein a plane perpendicular to their parallel refracting edges and therebyopen with respect to one anotliel angularly or like a fan. Thismeasuring device is founded on the following principle: A luminous rayIt, Fig. 3, passing through the prism l is deviated or retracted to l",being bent toward the base of the prism. Then the prism I) is moved tothe right or left of a plane perpendicular to its base and through itsret'racting edge, in this instance the vertical plane, the ray R becomesrefracted to a greater extent, that is, through a wider angle. In theposition of the prism 7), the ray It. is deviated to r, and in theposition p, to r1. The deviation of the ray It increases not only withthe increase in the angle of rotation of the prism P, but to a greaterextent, so that equal successive angles of rotation of the prism produceincreasing deviation, each greater than the preceding one. It is uponthis fact and action that our novel measuring device is based. One prismalone, however, is not suiicient to constitute a proper measuringdevice, not only by reason of coloring the images, (chromaticaberrations) but chiefly on account of the deformation of the images,the deformation being so great as to destroy their details. Thisdeformation may be prevented by assembling two identical prisms andcausing them to rotate to equal extents in opposite directions, therebycompensating the deformation, and to this end the measuring device willassume the form shown in Fig. 4. Ttk is still necessary, or desirable,to obviate the coloring of the images, due to dispersion. rThis may bedone in two ways, either by using two acliromatic prisms, or byinserting a third stationary prism which is termed the neutralizerbetween two prisms P. This third, stationary. prism may have an angletwice that of the movable prisms, or may be of flint or crown glass.Such an arrangement is shown in F ig. 5 which is the preferred form, andthe system of three prisms will be equal to a glass having parallelfaces, when the laterally movable prisms are' in their initial or closedposition.

The construction may be made general by adopting two movable prismshaving different angles, in which case the stationary neutralizing prismmust have an angle equal to the sum of the angles of the two movableprisms.

lf the three prisms are all of the same kind of glass, dispersion willbe produced when the two movable prisms have reached their usefulmaximum movement or rotation, which may be 400 or thereabout, for eachprism. In this case it will be necessary either to make all the prismsachromatic, or make the neutralizer of flint or crown glass with an ange capable of correcting, slightly in excess, the dispersing power of thetwo movable prisms when in their initial or closed position, and notquite capable of fully correcting the defect when the two movable prismshave been moved to their maximum extent.

lt will be understood that in order to always obtain perfect images themovable prisms should rotate by slightly different amounts, and thisdifference must be determined by experiment for each instrument. Thisdifference in the angle or speed of rotation of one of the movableprisms with respect to the other, will be, of course, less when the twoprisms have a different angle of refraction, as in the general caseabove referred to, and it will be an inverse function of said differencebetween the angles of refraction. 1t will also be necessary to determineit by experiment for each di'erence of angular amplitude and in eachinstrument. Tn this measuring device the luminous ray is deviated by aslight movement of the movable prisms, and as already remarked, isdeviated by an amount constantly increasing with' each unit increase ofopening of the prisms or rotation from their initial position. Tn knownmeasuring devices the luminous ray, under the same conditions, hasalways an equal deviation. Consequently in this device in order toobtain a uniform rate of deviation of the ray for equal angularmovements of the prisms, it will be necessary to eifect a rapid movementof rotation of the prisms at the beginning of their movement from theirinitial positions, and a slower one toward the end of their movement. lnother words, the speed of rotation varies inversely as the angle betweenthe two prisms, while in known devices the angle of rotation of the twoprisms must be constant, or nearly so.

The closed measuring device is mounted for viewing objects at thegreatest distance and its rotation is the greater the nearer the objectobserved, the maximum distance of the object corresponding to a minimumrotation of the prisms, and the minimum distance to the maximumrotation. Tt is also known that the displacement of the image of theobject observed greatly increases as the object is approached. From thisfact combined with the manner of operating the measuring device abovedescribed it results that :-a. ln known measuring devices the movementof the prisms and consequently the displacement of the scales fixedthereto, is relatively small for a distant object approaching, forinstance from 6,000 to 5,000 meters and considerably greater foranobject moving by the same amount but closer, for instance approachingfrom 3,000 to- 2,000 meters. o. In the measuring device made inaccordance with our present invention, the rotation of the prisms andconsequently the displacement of the measuring scales is somewhatincreased for distant objects and considerably reduced for closer ones.Therefore the scales in the known measuring devices must be graduatedwith lines drawn very close to one another for distant objects, and withlines wider apart the nearer the object. ln the present measuring devicethe scales are graduated uniformly or practically so, owing to thecompensation for the displacement of the image and for the rotation ofthe prisms, which rota-tion must decrease as the object is approached.Moreover, as the decrease in the spaces between thelines of the scalesfor close objects in the known forms is much greater than theinadjusted, then, after the displacement of the prisms of the measuringdevice, in order to cause the two parts of the image of the viewedobject to coincide or register in the field of the eye piece of thetelemeter, the field of the eye piece of the rectifying device isobserved, and. it will be found that the lower scale has been displaceddue to the rotation of the prisms of the measuring device. rIhedisplacement of this scale read by means of the upper scale or vernier,the position ot' which has not changed, is in direct proportion to thedisplacement of the prisms of the measuring device, and consequently tothe distance of the viewed object; the extent of this displacementchecks the reading effected by the measuring device.

The prisms 10 and 11 are illumined through the slots 29 and 30 providedin the casing 31 of the telemeter, Figs. 7 and 12. rllhese openings maybe circular, as shown in dotted lines in Fig. 12, and may be providedwith lenses in order to concentrate a greater quantity of light on theprisms 10 and 11.

The mounting of the instrument inside a protecting tube 31 is such as torender the instrument insensible to or unaffected by either the elasticor the permanent deformations of the tube, and especially those changesdue to temperature variations. This is attained by causing the wholetelemeter to rest on four points, placed in pairs, and the points of apair diametrically opposite and located on two vertical diameters sodistanced from the center of the telemeter that its weight is equallydistributed on both sides ot these supports.`

rlhe points of support are on four steel balls 32 located in steel seats33 mounted in or connected to the intermediate rings 34 of the telemeterbody. These balls also seat in plates 35 secured by screws 3G, Fig. 13,to the outside of the tube 31, Figs. 11, 12 and 13. The radii ofcurvature of the seats 33 is slightly greater than the radius of theballs 32, so that the latter contact with the seats at one point only.rtherefore, whatever the dilation of the tube 31 it will not produce anydeformation of the telemeter body. Even torsion or fleXure (especiallythe bending in a horizontal plane so harmful to optical mechanism) ofthe tube 31 is not transmitted to the telemeter body, owing to saidsuspension at the :tour points with the play between the balls and theirseats.

lV@ claim 1. ln a telemeter, the combination with an opaque sector, of atotally refiecting prism composed of two portions cemented together, theplane of cementation lying in the plane of reflection of said sector insaid. prism.

2. ln a telemeter, the combination wit. an opaque sector of a totallyreflecting prism composed of two portions cemented to- 7gether, saidsector positioned proximate the upper half of the emergent tace of theprism, and the plane of cement-ation lying in the plane of reflection ofsaid sector in said prism.

3. ln a telemeter, the combination with an opaque sector, of a totallyreflecting rightangular prism composed of two portions cemented togetherin a plane parallel its hypotenuse and the sector positioned oppositethe end of said plane perpendicular to the hypotenuse.

4f. ln a telemeter, the combination with a thin opaque sector, of atotally reflecting right-angular prism composed of two portions cementedtogether in a plane parallel to its hypotenuse, said sector positionedperpendicular to and substantially bisecting one half or the hypotenuseor emergent face of the prism and opposite one end of the plane ofcementation.

5. In a telemeter, the combination with a two part cemented totallyreflecting prism, of an opaque sector cooperating in conjunction withthe plane of cementation of said prism to separate the images distinctlyinto two portions and avoid the formation of phantom images.

6. ln a telemeter, a measuring device comprising a pair of prismsperpendicular to the optical axis of the telemeter and oppositelyrotatable in a plane perpendicular to their refracting edges.

7. ln a telemeter, a measuring device comprising a pair of prisms in andperpendicular to the optical axis of the telemeter and oppositelyrotatable in planes perpendicular to their refr-acting edges atdifferent angular speeds.

8. In a telemeter, a measuring instrument comprising a pair of prisms inand perpendicular to the optical axis of the telemeter and oppositelyrotatable in planes perpendicular to their refracting edges, and meansto chromatically correct said prisms.

9. ln a telemeter, a measuring instrument comprising a pair of prisms inand perpendicular to the optical axis of the telemeter and oppositelyrotatable in planes perpendicular to their refracting edges, said prismsbeing movable at different angular speeds and means to chrolnaticallycorrect said prisms.

10. ln a t-elemeter, a measuring instrument comprising two prisms in andperpendicular to the optical axis of' the telemeter and a third prismlocated between them whose refracting angle is substantially equal tothe sum of the refracting angles ofthe other two prisms.

11. In a telemeter, a measuring instrument comprising two equal parallelprisms in and perpendicular to theoptical axis of the telemeter androtatable in planes perpendicular to their refracting edges, and a thirdinverted prism located between them whose reti-acting angle is equal tothe sum of the refracting angles of the parallel prisms.

12. In a telemeter, a measuring device comprising two equal righttriangle prisms in and perpendicular to an optical axis ot thetelemeter, and a third inverted prism located between them whoseretracting angle is double the refracting angle oil one otl the parallelprisms said parallel prisms being cppositely rotatable in planesperpendicular to their refracting edges.

13. In a telemeter, a measuring device comprising two equal righttriangle prisms in and perpendicular to the optical axis o't' thetelemeter, and a third inverted prism located between them whosereti-acting angle is double the ref'racting angle of one otl theparallel prisms said parallel prisms being oppositely rotatable inplanes perpendicular to their reti-acting edges at different anglilarspeeds.

l-t. In a telemeter, a measuring device comjjirising two equal righttriangle prisms in and jiierpendicular to an optical axis of thetelemeter, and a third inverted prism located between them whoserefracting angle is double the refracting angle ot one oit the parallelprisms said parallel prisms being' oppositely rotatable in planesperpendicular to their retracting edges and whose outer :faces areparallel to one another' when in Zero position.

15. In a telemeter, a measuring device comprising a pair of prisms inand perpendicular to the optical axis ot the telemeter oppositelyrotatable in planes perpendicular' to their relracting edges atditlierent angular speeds, and a glass having plane parallel faces inand perpendicular to the optical axis pivoted to swing at an angle tosaid axis to correct for errors arisingin de'f'ormation of theinstrument.

1G. In a telemeler, a measuring instrument comprising` a pair of prismsin and perpendicular to the optical axis of' the telemeter andoppositely rotatable in planes perpendicular to their refracting edges,said. prisms movable at different angular' speeds and means tochromatically correct said prisms and a glass having plane parallelfaces in and perpendicular to the optical axis pivoted to swing at anangle to said axis to correct for errors arising in deformation of theinstrument.

17. In a telemeter, the combination with the erecting prisms thereof;ot' a measuring device to one side of said prisms, comprising parallelequal, right angle prisms in and perpendicular to the optical axis ofthe telemeter oppositely movable at different angular speeds in planesperpendicular to their retracting edges and a stationary inverted prismwhose ref'racting angle is equal to the sum of the refracting anglesoit' the movable prisms, the outer faces of which said movable prismsare parallel when in zero )osition and a glass having plane parallel.taces to the other side of said erecting prisms in and perpendicular tothe optical axis of the telemeter and mounted to move at angles to saidaxis.

18. The combination with a telemeter having objective prisms, eachhaving a reflector on a portion of its face, of an eye piece, a pair oifcrossed reflecting prisms reflecting into the same, a prism on each sideo said crossed prisms, having an index on one ot its faces, means toillumine the latter prisms to direct the light to the said reflectorswhich in turn reflect the light to the crossed prisms.

19. The combinatitm with a telemeter having two objective prisms, onehaving a retlector on the upper half ot' its forward laci and the otheron the lower hallE of its forward face; of an eye piece, a pair ofcrossed juxtaposed prislns reflecting directly into the same, a prism oneach side of said crossed prisms, less in height than one of them, anindex on the emergent face of each of said latter prisms directed towardsaid reflectors and means to sejiarately illumine the latter prisms.

Q0. The combination with a telemeter having two oppositely situatedobjective prisms, ot' a reflector on the upper halt of the ilicidentface of one and the lower half ot' the incident tace of the otherslight-ly inclined to said face, an eye piece, a pair ot super-posedjuxtaposed crossed prisms reflecting directly into said eye piece, aprism opposite each of the crossed prisms of less height than saidcrossed prisms and located respectively above and below the optical axisot' the telemeter, oneI of said prisms having` engraved on its emergentface a scale and on the einer'- gent face oi the other, a vernier, meansto separately illumine the latter prisms whereby they will direct light.to the reflectors which in turn will reflect to the crossed prisms thatagain reflect to the eye piece where the scale and Vernier are viewed inproper relation to one another.

21. The combination with a telemeter having light receiving prisms, eachhaving a reflector on a portion ot its face, of an eye piece, a pair ofcrossed reflecting prisms reflecting into the same, a side prism on eachside ott said crossed prisms, having an index on one ot its faces, meansto illumine the latter prisms and direct the light reflected 'from saidside prisms to the said reflectors which in turn reflect the light tothe crossed prisms, and means to deflect the rays -from one of thereflectors into a parallel p'ath before reaching the crossed prisms.

22. rIhe combination with a telemeter having light receiving prisms,each having a reflector on a portion ot' its f'aee, ot an eye piece, apair of crossed reflecting prisms refleeting into the same, a prism o-neach side of said crossed prisms, having an index on one of its faces,means to illumine the latter prisms to direct the light to the saidreflectors Which in turn reflect the light to the crossed prisms, andoptical means to compensate for deformations of the telemeter.

23. The combination with a telemeter having two oppositely situatedobjective prisms, of a reflector on the upper half of the incident faceof one and the lower half of the incident face of the other slightlyinclined to said face, an eye piece, a pair of superposed juxtaposedcrossed prisms refiecting directly into said eye piece, a prism oppositeeach of the crossed prisms of less height than said crossed prisms andlocated respectively above and below the optical axis of the telemeter,one of said prisms having engraved on its emergent face a scale and onthe emergent face of the other, a Vernier, means to separately illuminethe latter prisms Whereby they will direct light to the reflectors whichin turn will reflect to the crossed prisms that again reect to the eyepiece Where the scale and Vernier are viewed in proper relation to oneanother, and a rotatable glass having plane parallel faces in the pathof the rays reflected by one of the reflectors.

In testimony that We claim the foregoing as our invention, We havesigned our names in presence of two subscribing Witnesses.

VIRGILO COLZI. FELICE BARDELLI. Witnesses:

PIERO GIANoLis, EUGENIO G. B. CosnTTA Fonzro.

Copies of this patent may be obtained for ve cents each, by addressing'che Commissioner of Patents, Washington, lD. C.

